RU2326215C1 - Reinforcement bars muff joining with help of expanding bonding agent - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention refers to the sphere of construction dealing with issues related to joining reinforcement bars of reinforced concrete structures. The given method of reinforced bars muff joining with the help of expanding bonding agent provides for stiff and equal in strength fixation of the bars without impairing their useful mechanical and deformation properties with due respect for coaxiality and without any restrictions as for the diameter and cross section of the bars being joined and without the necessity to engage other speciality professionals for performance of the reinforcement assembly operations. The solution suggested consists in joining butted reinforcement bars with the help of a muff in the form of a sleeve made of a tube with the inner surface either plain or shaped and subsequent injection of tensive bonding agent into the cavity formed by the inner surfaces of the tube and the outer surfaces of the reinforcement bars butted.

EFFECT: stiff and equal in strength fixation of the bars without impairing their useful mechanical and deformation properties with due respect for coaxiality and without any restrictions as for the diameter and cross section of the bars being joined and without the necessity to engage other speciality professionals for performance of the reinforcement assembly operations.

2 cl, 2 dwg

Description

The invention relates to the field of construction, in particular to compounds of reinforcing bars in reinforced concrete structures.

It is known the connection of reinforcing bars lap (without welding) (SNiP 2.03.01-84 * "Concrete and reinforced concrete structures", - M .: GOSSTROY USSR, 1989 (p. 63-64)) (1). This connection is a bypass of parallel-located abutting rods beyond the end faces of each other by the length of the anchoring. The range of application of these compounds is limited mainly by compressed structural elements. These joints are undesirable in bending, as well as eccentrically compressed elements and are unacceptable in stretched. The diameter of the joined rods is also limited to 36 mm, there is an overspending of steel within the joint length. A significant drawback is the shift of the centers of gravity of the cross-section of the rods in the vertical plane and, as a consequence of this, the loss of stability of the connection when the protective layer of concrete is destroyed.

Known joint reinforcing bars for welding type "C" (GOST 14098-91 "Connection of welded reinforcement and embedded products of reinforced concrete structures. Types, structures and sizes." - M .: USSR State Committee for Construction and Investments, 1992 (Table 4- 17)) (2). Joints of this type require appropriate welding equipment and a welder of the appropriate qualification, which increases the complexity, mechanical intensity and cost of construction and installation works. As a result of heating, the mechanical properties of the steel are lost, which limits the use of this type of joint for reinforcing steels of a class higher than A-IV, as well as thermally hardened or hardened by exhaust hoods. These connections are not technologically applicable for cable-type fittings.

It is known to connect reinforcing bars using couplings with tightening with locknuts or with filling gaps with epoxy resin, proposed by the Japanese company Sumitomo (K.V. Mikhailov, G.I. Berdichevsky, Yu.S. Volkov and others. Pre-stressed reinforced concrete (based on materials IX Congress of the FIP) .- M .: Stroyizdat, 1986 (p. 42-44)) (3). This type of connection is limited to use only for reinforcing bars with a special screw profile, it requires the presence of torque wrenches and special hydraulic devices for injecting epoxy resin under pressure into the gaps of the threaded connection.

It is known to connect reinforcing bars using couplings with threads on the inner surface, filled with mortar or concrete EP 1424453 A1 (KINTSCHER M.), 02.06.2004 (p.12-20) (4). The disadvantage of this compound is the shrinkage process inherent in mortars and concrete. Shrinkage leads to the appearance of gaps at the interface between the reinforcement-concrete and concrete-coupling media, which, in turn, increases the deformability of both the joint and the building structure at the joints of the reinforcement. The deformability of the reinforcement connection makes the structure unsuitable for operation under the condition of crack resistance.

The objective of the proposed sleeve joint of reinforcing bars on an expanding binder is to create a rigid, equal strength connection of the reinforcement with preserving its mechanical and deforming properties, maintaining alignment and removing restrictions in the diameter and profile of joined rods, as well as ensuring the installation of the reinforcement without involving additional workers .

The problem is solved by connecting the reinforcing bars through the sleeve, which is a sleeve made in the form of a pipe, followed by injection of an expanding binder into the chamber formed between the inner faces of the pipe and the outer faces of the reinforcement.

The proposed method for connecting reinforcing bars in the form of a sleeve joint of reinforcing bars on an expanding binder is illustrated by drawings, in which Fig. 1 shows a longitudinal section of a sleeve joint of reinforcing bars on an expanding binder, and Fig. 2 shows a cross section 1-1.

Positions in figure 1, 2 are indicated:

1) abutting reinforcing bars;

2) a chamber filled with an expanding binder;

3) a sleeve in the form of a pipe with a profiled or smooth inner surface;

4) guide section of the sleeve;

5) an expanding binder;

6) holes in the sleeve for injection of the expanding binder;

7) section of the sleeve, fixing the free movement of reinforcing bars;

8) locking elements.

The device consists of a sleeve, which is a sleeve (pos. 3) from 3d to 60d long (d is the diameter of the joined rods (pos. 1)), made in the form of a pipe with an inner diameter from 1.1d to 3d with a profiled or smooth inner surface. The sleeve (pos. 3) has guide sections (pos. 4) from 0.1d to 3d in length, a section (pos. 7) that fixes the free movement of reinforcing bars (pos. 1) from 0.5d to 5d in length and a camera (pos. 2 ) filled with an expanding binder (item 5). The sleeve in the form of a pipe is made with holes (pos.6) for injection of an expanding binder (pos.5). The length of the sleeve (item 3) is determined by the strength properties of the expanding binder (item 5) and the range of reinforcement.

The operation of the device consists in transferring the load from one of the joined reinforcing bars (item 1) to another by means of a connecting sleeve in the form of a pipe (item 3) and the ability of the expanding binder (item 5) to solidify and increase in volume. As a result of the increase in the volume of the binder (pos. 5), a voltage of up to 20 MPa is created between the outer faces of the reinforcing bars (pos. 1) and the inner faces of the sleeve (pos. 3). The voltage value depends on the magnitude of the expansion of the binder (item 5), as well as the strength and deformation properties of the sleeve material (item 3). Pressure on the walls of the sleeve (pos. 3) and the surface of the reinforcement (pos. 1) causes a significant increase in the friction forces at the boundaries of the media of the joined reinforcing bars (pos. 1), a binder (pos. 5) and the liner (pos. 3). The longitudinal forces acting in the reinforcing bars (item 1) are perceived by the forces of friction on the contact surfaces and are transmitted through the layer of expanding binder (item 5) to the walls of the sleeve (item 3). A significant part of the stresses is transmitted through the ends of the guide sections (pos. 4) and due to the manifestation of the effect of jamming of the reinforcement between the walls of the sleeve (pos. 3). The volumetric stress state that occurs during the expansion of the binder (item 5) during the hardening process, contributes to its self-compaction. The expansion of the binder (pos. 5) eliminates the possibility of free movements in the places of contact of the media of the joined reinforcing bars (pos. 1), the binder (pos. 5) and the sleeve (pos. 3). Fixing the reinforcing bars (pos. 1) in the design position is provided by the guide sections of the sleeve (pos. 4) and the section fixing the free movement of the reinforcing bars (pos. 7). The exclusion of possible movements of the reinforcing bars (item 1) during the hardening period of the expanding binder (item 5) is provided by the locking elements (item 8). The expanding binder (pos. 5) is injected into the chamber (pos. 2) formed between the inner faces of the liner (pos. 3) and the outer faces of the reinforcement (pos. 1) through openings (pos. 6). The equal strength of the connection and the reinforcing bars (item 1) is ensured by the selection of the cross-sectional area of the sleeve, made in the form of a pipe (item 3).

Using the proposed invention in the form of a sleeve joint of reinforcing bars on an expanding binder will reduce the consumption of bar reinforcement in relation to the most commonly used joints without overlap without welding, and will increase the reliability of reinforced concrete building structures at the joints of the reinforcement. This invention solves the problem of coaxial connection of reinforcing bars while preserving the physical properties of reinforcing steel, low cost of joint and technological simplicity, makes it possible to expand the scope of bar reinforcement in prestressed concrete elements. The application of the proposed device will increase the speed of reinforcing work, especially in cases where a rigid (such as welded) connection of the reinforcement is necessary and reduce the costs of construction organizations on the wages of workers (in particular the welder) and the purchase of additional equipment. The use of an expanding binder significantly increases the strength and deformation characteristics of the reinforcement joint.

Claims (1)

A sleeve joint of reinforcing bars on an expanding binder, characterized in that it contains a coupling, which is a sleeve from 3d to 60d in length (d is the diameter of the joined bars), made in the form of a pipe with an internal diameter from 1.1d to 3d with profiled or smooth the inner surface, while the sleeve has a section that fixes the free movement of reinforcing bars from 0.5d to 5d in length, guide sections from 0.1d to 3d in length, stop elements and a chamber filled with an expanding binder samonapryazheniem to 20 MPa.

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